Electromagnetic signal transmission



Sept. '3, 1929. E. BELIN ELECTROMAGNETIC SIGNAL TRANSMISSION Filed Nov. 6, 1925 Patented Sept. 3, 1929.

UNITED STATES 1,721,194 PATENT OFFICE.

EDOUARD BELIN', OF PARIS, FRANCE.

ELECTROMAGNETIC SIGNAL TRANSMISSION.

Application filed November 6, 1925, Serialli'o. 67,706, and in France September 7, 1924.

This invention relates to improvements in receiving and transmitting apparatus of synchronous electrical transmission systems, and has as its object the variation of speed of aparatus without sacrificing. of synchronism or destroying the capacity of unauthorized persons to intercept or otherwise receive mat ter transmitted.

In my Patent No. 1,657,366, means is de scribed for maintaining secret the transmission .of a document' carried by a cylinder and reproduced upon a recording surface carried by another cylinder. Among the conditions therein set out as necessary for means of this type is that the speed of rotation of the cylinders should, when transmitting a document,

be absolutely uniform throughout the trans-' mission.

Cases may, however, arise where, having found the periodicity of the secret transmission, this may be utilized for finding out the communication by reconstructing a document received in periodic fractions. An effective means of obviating this forms the subject of this invention.

According to this invention the speed of the cylinder is varied from one turn to another.

Such variation is easily obtained, for example, by automatically inserting gearing through the translator (see Figure 2 of the drawing of said patent) or through another member according to predetermined code which may be variable as is that of the translator.

In the accompanying drawing,

Fi ure 1 is a view in side elevation of spec changing apparatus embodying thefeatures of the present invention. I

Figure 2 is a transverse section taken on the plane indicated by line 22 of Fi ure'l, and looking in the direction shown by the arrow. M

Figure 3 is a similar section taken on the lane indicated by line 33 of Figure 1 and ooking in the opposite direction.

Referring to the drawings b numerals, 1 indicates the main drive sha t, and-2 the shaft connected to and actuating the receiving'and transmitting cylinders. Transmission and reception of light explored surfaces through circuits governing instrumentalities of transmission wherein the surface being ex-- transmitting end, as the case may be. The

variation in movement between the shafts 1 and 2 may be effected by any of numerous types of devices or mechanisms, a simple form being illustrated in the accompany drawing; The device shown consists of a yoke 6 aving one of its arms journaled on shaft 1 and its other arm journaled on shaft 2, the shafts being in anal alinement, but not in engagement with each other. Fixed to the shaft 1 is a gear 3, and fixed to the shaft 2 is a gear 4, said gears bein preferably located within the yoke 6, an arranged to mesh with the corresponding parts of a companion gear 5. The ear 5 is ournaled in the yoke 6 and is ma e up of two complete gear areas or sections formed integral or appropriately fixed to each other and one of greater diameter than the other proportional to the difference in diameter between the gears 3 and 4. The difference in diameter between gears 3 and 4 may be greater or less, and the difference in diameter of the two sections of the companion gear 5 will be proportionately varied, so that, as the gear be moved by the shaft V being 3 is driven, power will be transmitted through gear 5 to gear 4, and thence to shaft 2. As illustrated, the gear 3 is of less diameter than gear 4, so that the section of gear 5 intermeshing with gear 3 is of greater diameter than that section of gear 5 which meshes with gear 4. Hence, the speed of shaft 2 is slower than that of shaft 1 in the structure shown, but that is not a controlling factor and ted to gear 4 is subtracted; while, on the a crank, and, to this end, is provided with a laterally extending wrist pin 8 which-pivotally carries a link 7 extending to and pivotally engaging the yoke 6. The wrist pin 8 is adapted to be adjusted angularly about the peripheral portion of the gear 10, as by being detachably anchored in any one of apertures 9, 9, formed in said gear, so that variation in the timing of the variations in speed of shaft 2 may be effected by location of the pin 8 in any one of the several apertures 9. Variation in the throw of the link 7 may also be effected, if desired, by radial adjustment of the end of the link engaging the pin 8 by the location of the said pin in any of the apertures 9.

Thus it will be seen that, since the shaft 1 at the transmitter station is driven synchronously with the shaft 1 at the receiving station, that the shafts 2 at the respective stations will be also synchronously actuated, although actuated at variable and irregular speeds, so that an unauthorized effort to discover definite periodicity in the message transmitted will be frustrated.

It will thus be clear that the variations are not revealed by any special si nal and so a spy ap aratus adjusted upon t e periodicity of the cat per unit of time and so rotating evenly at constant speed) wil not be adapted correctly to receive the emission derived from a cylinder rotating sometimes quicker and sometimes slower than it.

. This arrangement can clearly not be applied to continuous tinted documents occupying in fact the entire surface. Per contra for black documents upon white-line, writing, characters, or the like, the variation of speed will produce a disagreeable efiect, i. e.,

will give a document whose value will no longer be regular. This defect is however of small account especially with a certainty of secrecy for even if disagreeable the text will be readable and its authenticity can be recognized.

It is possible still to increase the difliculty by varying the speed of the cylinder during a turn.

It is possible also to arrange the changes of speed so that they do not coincide with the commencement of each turn.

To recapitulate the improvement aimed at in the present application is characterized by the employment of variations in the speed of the cylinders, both between turns as dura redetermined code.

aving now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is 1. In electro-magnetic apparatus for message transmission by exploration employing synchronously movable exploration surfaces and means for exploring the same, the combination with a surface actuator, a driver therefor, means for imparting movement from the driver to the actuator at a speed relatively different from that of the driver, and means for varying such speed.

2. In electro-magnetic apparatus for message transmission by exploration emplo ing synchronously movable exploration surfaces and means for exploring the same, the combination with a surface actuator, a driver therefor, means for imparting movement from the driver to the actuator at a constant speed relatively difierent from that of the driver, and means for irregularly varying such speed.

3. In electro-magnetic apparatus for message transmission by exploration employing synchronously movable exploration surfaces and means for exploring the same, the combination with a surface actuator, a driver therefor, means for imparting movement from the driver to the actuator at a constant speed relatively different from that of the driver, means for irregularly varying such speed, and means for adjusting the last named means.

4. In the art of picture and facsimile transmission between stations, means for maintaining secrecy of transmission comprising the combination with a movable exploration surface and means for exploring the same at each station, of means for-effecting synchronized movements of the several surfaces and means for effecting a variable speed thereof while maintaining synchronism.

5. In the art of picture and facsimile transmission between stations, means for maintaining secrecy of transmission comprising the combination with a rotatable exploration surface and means for exploring the same at each station, of means for effecting synchronized rotary movements of the several surfaces, and means for causing said movements to be varied at each revolution.

6. In the art of picture and facsimile transmission between stations, means for maintaining secrecy of transmission comprising the combination with a movable cylindrical exploration surface and means for exploring the same at each station, of means for effecting synchronized movements of the surfaces, means for varying the speed of movement of the same, and means for producing this variation according to a predetermined law.

7 In the art of secret electromagnetic picture and facsimile transmission by exploration employing synchronously movable record surfaces and means for exploring the same, the method which comprises varying the speed of synchronized movements of transmitting and receiving record parts.

8. In the art of secret electromagnetic picture and facsimile transmission by exploration employing synchronously movable record surfaces and means for exploring the same, the method which comprises irregularly varying the speed of synchronized movements of transmitting and receiving record parts.

9. In electromagnetic picture and facsimile transmission by exploration employing synchronously movable exploration surfaces and means for exploring the same, the combination with driving means and means for actuating the exploration surfaces, of means therebetween for imparting from the driving means Variable motion to the surface actuating means. Y v

10. In electromagneticipicture and facsimile transmission by exploration employing synchronously movable-exploration surfaces and means for exploringithe $3 9, the combination with driving means and means for actuating the exploration surfaces, of means therebetween for imparting from the driving means irregularly variable motion to the surface actuating means.

11. In electromagnetic picture and facsimile transmission by exploration embodying synchronously movable exploration surfaces of two dimensions and means for exploring the same, the combination with regularly actuated driving means and means for actuating the exploration receiving surfaces, of means therebetween for imparting from the driving means variable motion to the actuating means.

In testimony whereof I afiix my signature.

EDOUARD BELIN. 

